The present invention relates to a jam clearance and unit pullout means effectively used when a jam that occurs, for example, between a paper conveyance unit and a paper feed tray unit provided in an image forming apparatus such as a copier and an image scanner.
In general, an electrophotographic image forming apparatus such as a copier and an image scanner comprises: a platen on which a document is set; an optical scanning system including a document illuminating lamp and a reflecting mirror, which are reciprocated under the platen, and also including a projection lens and a reflecting mirror, which are fixed; a rotational photoreceptor drum that is charged to a predetermined potential by a charging electrode; a developing unit that develops an electrostatic latent image formed on the photoreceptor drum, with toner; a transfer electrode that transfers the formed toner image onto a recording paper, which is a transfer sheet, conveyed toward the photoreceptor drum; a separation electrode; a discharge electrode; a fixing unit to fix the toner image transferred onto the recording paper surface; and a cleaning unit to remove residual toner and dust on the photoreceptor drum surface.
Predetermined toner images are successively recorded on the recording papers intermittently conveyed in a predetermined conveyance passage.
In the apparatus described above, the paper feed conveyance unit, fixing unit including a paper discharge roller and a plurality of paper feed tray units are constructed so that they can be respectively pulled out from the image forming apparatus. For example, when a paper jam occurs in the paper feed conveyance unit, the unit is pulled out for jam clearance, that is, the jammed recording paper is removed.
However, for example, in the case where a conveyed recording paper is jammed between the paper feed conveyance unit and the paper feed tray unit, the jammed recording paper is damaged when one of the units is carelessly pulled out. To remove the damaged recording paper from one of the units costs much labor. When the jam clearance operation is not performed completely, the successive recording papers are also jammed.
In the case where the image forming apparatus is constructed so that each unit can be pulled out, the following problems may be encountered: In the case where a plurality of units are carelessly pulled out at the same time, the balance of the apparatus is lost so that the apparatus falls down. Further, when the apparatus is designed, dead spaces are unnecessarily formed, so that the apparatus can not be made compact. Even when the units are overlapped so as to make the apparatus compact, there is a possibility that the photoreceptor drum or another unit is damaged when each unit is not pulled out in a predetermined order.
The present invention is to overcome the above disadvantages. It is an object of the present invention to provide an image forming apparatus characterized in that: even when a recording paper is jammed between two units, it can be easily, positively and quickly removed without being damaged; and when the units are pulled out for jam clearance, there is no possibility that the balance of the apparatus is lost, and that the units are pulled out in wrong order thereby affecting other units.